It is in the news that a campaign group Led by Donkeys has made prank calls to politicians to show how willing they are to work with commercial companies for £10,000 a day. Former minister Stephen Hammond's spokesperson is quoted as describing this as “illegal publication of a private conversation”.
What law(s) could have been broken here, and by whom (the recorder or the publisher)? It seems like the sort of prank call that has been the mainstay of many TV programs over the years, and I have not heard of any police investigations into those so it is not obvious that this is against the law.